Isfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231Heat Transfer Enhancement of Al2O3âH2O Nanofluid Free Convection in Two-Phase Flow with Internal Heat Generation Using Two Dimensional Lattice Boltzmann MethodHeat Transfer Enhancement of Al2O3âH2O Nanofluid Free Convection in Two-Phase Flow with Internal Heat Generation Using Two Dimensional Lattice Boltzmann Method118322210.47176/jcme.40.2.6202FAA. R. RahmatiE. KashaiJournal Article20221231A two-phase lattice Boltzmann model considering the interaction forces of nanofluid has been developed in this paper. It is applied to investigate the flow and natural convection heat transfer of Al2O3–H2O nanofluid in an enclosure containing internal heat generation. To understand the heat transfer enhancement mechanism of the nanofluid flow from the particle level, the lattice Boltzmann method is used because of its mesoscopic feature and numerical advantages. By using a two-component lattice Boltzmann model, the heat transfer enhancement of the nanofluid is analyzed through incorporating the different forces acting on the nanoparticles and the base fluid . The effects of interaction forces, nanoparticle volume fractions (0.0-0.05), and internal and external Rayleigh numbers (103-106) on the nanoparticle distributions and heat transfer characteristics are investigated. The average Nusselt number increases with the increase of nanoparticle volume fraction and Rayleigh number. We also compared and analyzed adding internal heat generation on the nanoparticles and the base fluid separately, and it was found that by considering heat generation on the base fluid, it mostly affects the temperature field, and by considering that on nanoparticles, it mostly affects the stream field.A two-phase lattice Boltzmann model considering the interaction forces of nanofluid has been developed in this paper. It is applied to investigate the flow and natural convection heat transfer of Al2O3–H2O nanofluid in an enclosure containing internal heat generation. To understand the heat transfer enhancement mechanism of the nanofluid flow from the particle level, the lattice Boltzmann method is used because of its mesoscopic feature and numerical advantages. By using a two-component lattice Boltzmann model, the heat transfer enhancement of the nanofluid is analyzed through incorporating the different forces acting on the nanoparticles and the base fluid . The effects of interaction forces, nanoparticle volume fractions (0.0-0.05), and internal and external Rayleigh numbers (103-106) on the nanoparticle distributions and heat transfer characteristics are investigated. The average Nusselt number increases with the increase of nanoparticle volume fraction and Rayleigh number. We also compared and analyzed adding internal heat generation on the nanoparticles and the base fluid separately, and it was found that by considering heat generation on the base fluid, it mostly affects the temperature field, and by considering that on nanoparticles, it mostly affects the stream field.https://jcme.iut.ac.ir/article_3222_d569eab9b94c4898137234989e684dd7.pdfIsfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231Simulation of Simplified Computational Model of Jacket Structure with Timoshenko Cantilever Beam and Experimental SignatureSimulation of Simplified Computational Model of Jacket Structure with Timoshenko Cantilever Beam and Experimental Signature1937322310.47176/jcme.40.2.8151FAF. HosseinlouJournal Article20221231Today many complex models, typically finite element models, have been employed in the analysis of jacket offshore structures. However, these comprehensive models are not readily adopted in engineering practice, especially during the preliminary design stage. As the dynamic analysis of jacket platforms is very complicated, it will be very advantageous to make a simplified computational method to assess dynamic performance of such structures. In this work a refined simplified model has been utilized to calculate dynamic responses of jacket platforms. In this regard, the model simplification based on the vibration modal data and Timoshenko’s beam equation has been employed to overcome the uncertainty problem in modeling. According to the curve fitting method on the set of frequency response functions to derive modal parameters, the concept of power spectrum density has been also used to confirm the proposed computational model.In this regard, first the behavior of the physical model in the frequency domainhas been presented and compared with the spectral results obtained from the simplified model based on Timoshenko beam. Because the modal test of the physical model was performed under the force of white noise, the dynamic responses of the simplified model were also extracted under the force of white noise using MATLAB software. In this paper, an applied mathematical model has been produced, and it has been demonstrated that the refined simplified model can reflect the real structural features.Today many complex models, typically finite element models, have been employed in the analysis of jacket offshore structures. However, these comprehensive models are not readily adopted in engineering practice, especially during the preliminary design stage. As the dynamic analysis of jacket platforms is very complicated, it will be very advantageous to make a simplified computational method to assess dynamic performance of such structures. In this work a refined simplified model has been utilized to calculate dynamic responses of jacket platforms. In this regard, the model simplification based on the vibration modal data and Timoshenko’s beam equation has been employed to overcome the uncertainty problem in modeling. According to the curve fitting method on the set of frequency response functions to derive modal parameters, the concept of power spectrum density has been also used to confirm the proposed computational model.In this regard, first the behavior of the physical model in the frequency domainhas been presented and compared with the spectral results obtained from the simplified model based on Timoshenko beam. Because the modal test of the physical model was performed under the force of white noise, the dynamic responses of the simplified model were also extracted under the force of white noise using MATLAB software. In this paper, an applied mathematical model has been produced, and it has been demonstrated that the refined simplified model can reflect the real structural features.https://jcme.iut.ac.ir/article_3223_423dc7408c6af48b999b1146d4722d9d.pdfIsfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231Buckling Analysis of Non-Prismatic Columns Subjected to Non-Uniform Loading Using the Meshless Local Petrov-Galerkin MethodBuckling Analysis of Non-Prismatic Columns Subjected to Non-Uniform Loading Using the Meshless Local Petrov-Galerkin Method3956322410.47176/jcme.40.2.8381FAF. F. HeidargheitaghiM. H. M. H. Ghadiri RadM. KazemiJournal Article20221231Continuously varying cross-section members have found wide applications in engineering for cost and resistance optimization. Since steel structures generally have more slender members compared to concrete structures, buckling analysis of steel members is of more importance. Determining the critical load of functionally varying cross-section columns using the analytical solution is a time-consuming process. In this paper, buckling analysis of non-prismatic steel columns is conducted using the meshless local Petrov-Galerkin (MLPG) method. In meshless methods, the scattered nodes are used rather than the elements to model the problem domain and its boundaries. The change of the inertia moment within the length of a column is characterized by introducing a power function with variable taper ratio and exponent. The radial basis function is used to discretize the differential equation governing the buckling. The penalty method is used for the imposition of the boundary conditions. Numerical examples of the critical buckling load for prismatic and non-prismatic columns using the proposed method are compared with the analytical solution, and the effectiveness of the MLPG method for buckling analysis of non-prismatic columns is validated. Also, buckling analysis of muscle column members subjected to non-uniform axial load is carried out to show the efficiency of the proposed method. The effect of several parameters such as non-uniformity of the load and variation of the cross-section on the buckling load of the column is discussed in details.Continuously varying cross-section members have found wide applications in engineering for cost and resistance optimization. Since steel structures generally have more slender members compared to concrete structures, buckling analysis of steel members is of more importance. Determining the critical load of functionally varying cross-section columns using the analytical solution is a time-consuming process. In this paper, buckling analysis of non-prismatic steel columns is conducted using the meshless local Petrov-Galerkin (MLPG) method. In meshless methods, the scattered nodes are used rather than the elements to model the problem domain and its boundaries. The change of the inertia moment within the length of a column is characterized by introducing a power function with variable taper ratio and exponent. The radial basis function is used to discretize the differential equation governing the buckling. The penalty method is used for the imposition of the boundary conditions. Numerical examples of the critical buckling load for prismatic and non-prismatic columns using the proposed method are compared with the analytical solution, and the effectiveness of the MLPG method for buckling analysis of non-prismatic columns is validated. Also, buckling analysis of muscle column members subjected to non-uniform axial load is carried out to show the efficiency of the proposed method. The effect of several parameters such as non-uniformity of the load and variation of the cross-section on the buckling load of the column is discussed in details.https://jcme.iut.ac.ir/article_3224_d4b983715018e1c0930387116b36ccef.pdfIsfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231Finite Difference Dynamic Stability and Liquefaction Analysis of Esphordi Mine Tailings Dam Implementing Non-Linear Elasto-Plastic Constitutive ModelFinite Difference Dynamic Stability and Liquefaction Analysis of Esphordi Mine Tailings Dam Implementing Non-Linear Elasto-Plastic Constitutive Model5779322510.47176/jcme.40.2.8792FAR. Salamat MamakaniA. AzhariJournal Article20221231Dynamic stability and liquefaction of tailings dams are great concerns for geotechnical engineers. In this study, the seismic response of the Esphordi mine tailing dam located in Bafgh seismic region of Yazd province is investigated. A finite-difference code (FLAC2D) is used to model the seismic liquefaction applying two constitutive criteria, namely Mohr-Coulomb and Finn-Byrne. For this purpose, a fish function is implemented into the code to simulate the non-linear elasto-plastic Finn-Byrne constitutive model. Horizontal and vertical displacements (subsidence) in the dam body, additional pore pressure, failure zones, and liquefaction due to seismic load were determined using the two selected criteria under the seismic load of the 6.4 magnitude earthquake occurred in 2005. Considering the type of behavioral model, Mohr-Coulomb and Finn-Byrne, the maximum horizontal displacement of 5 and 35 cm in the dam body and downstream, and subsidence of 4 and 23 cm at the dam crest and upstream are observed, respectively. Also, the calculated ratio of excess pore pressure (Ru), for both criteria, was less than the liquefaction limit (0.9), the maximum value of which was 0.7 for the Finn-Byrne criterion and 0.2 for the Mohr-Coulomb criterion. In general, the results show that considering the cumulative effect of the seismic load cycles in the Finn- Byrne model, this criterion provides a better understanding of the liquefaction phenomenon.Dynamic stability and liquefaction of tailings dams are great concerns for geotechnical engineers. In this study, the seismic response of the Esphordi mine tailing dam located in Bafgh seismic region of Yazd province is investigated. A finite-difference code (FLAC2D) is used to model the seismic liquefaction applying two constitutive criteria, namely Mohr-Coulomb and Finn-Byrne. For this purpose, a fish function is implemented into the code to simulate the non-linear elasto-plastic Finn-Byrne constitutive model. Horizontal and vertical displacements (subsidence) in the dam body, additional pore pressure, failure zones, and liquefaction due to seismic load were determined using the two selected criteria under the seismic load of the 6.4 magnitude earthquake occurred in 2005. Considering the type of behavioral model, Mohr-Coulomb and Finn-Byrne, the maximum horizontal displacement of 5 and 35 cm in the dam body and downstream, and subsidence of 4 and 23 cm at the dam crest and upstream are observed, respectively. Also, the calculated ratio of excess pore pressure (Ru), for both criteria, was less than the liquefaction limit (0.9), the maximum value of which was 0.7 for the Finn-Byrne criterion and 0.2 for the Mohr-Coulomb criterion. In general, the results show that considering the cumulative effect of the seismic load cycles in the Finn- Byrne model, this criterion provides a better understanding of the liquefaction phenomenon.https://jcme.iut.ac.ir/article_3225_9a0336252e95bcd1f50a6d636770a408.pdfIsfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231Numerical Study of the Effect of Nanofluid on Heat Transfer of a Channel in the Presence of Variable Magnetic Field with ObstaclesNumerical Study of the Effect of Nanofluid on Heat Transfer of a Channel in the Presence of Variable Magnetic Field with Obstacles8194322610.47176/jcme.40.2.8521FAP. GilavandH. R. HeidariJournal Article20221231In this paper, the effect of water- iron oxide (Fe3O4) nanofluid on a channel heat transfer in the presence of perpendicular to the flow variable magnetic field with creating axial obstacles using a mixed single-phasee model is investigated numerically. The effects of magnetic field are added to governing equations of ferrofluid by writing codes and the problem geometry is generated and networked in Gambit 2.4 software. The network used is constructed in a three-dimensional and the governing non-linear differential equations are solved according to the finite volume method by using the Fluent software. Also, the effect of parameters such as obstacles in the flow path, dimensionless number of magnetic field intensity and Reynolds dimensionless number on heat transfer have been studied. The results show that creating obstacles in the flow path causes turbulence in the fluid flow, which increases the overall heat transfer. Also, the application of a magnetic field on the magnetic nanofluid causes the penetration of the cool boundary layer in the central parts of the channel and with increasing the intensity of the magnetic field, the penetration of this layer increases. As a result, the amount of Nusselt number and heat transfer has increased, and this improvement in heat transfer and Nusselt number increases with increasing Reynolds number.In this paper, the effect of water- iron oxide (Fe3O4) nanofluid on a channel heat transfer in the presence of perpendicular to the flow variable magnetic field with creating axial obstacles using a mixed single-phasee model is investigated numerically. The effects of magnetic field are added to governing equations of ferrofluid by writing codes and the problem geometry is generated and networked in Gambit 2.4 software. The network used is constructed in a three-dimensional and the governing non-linear differential equations are solved according to the finite volume method by using the Fluent software. Also, the effect of parameters such as obstacles in the flow path, dimensionless number of magnetic field intensity and Reynolds dimensionless number on heat transfer have been studied. The results show that creating obstacles in the flow path causes turbulence in the fluid flow, which increases the overall heat transfer. Also, the application of a magnetic field on the magnetic nanofluid causes the penetration of the cool boundary layer in the central parts of the channel and with increasing the intensity of the magnetic field, the penetration of this layer increases. As a result, the amount of Nusselt number and heat transfer has increased, and this improvement in heat transfer and Nusselt number increases with increasing Reynolds number.https://jcme.iut.ac.ir/article_3226_587b9c032ab49cc557bf2a04e0b2794e.pdfIsfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231Statistical Analysis of Energy Harvesting From Functionally Graded Cantilever Beam with Piezoelectric LayerStatistical Analysis of Energy Harvesting From Functionally Graded Cantilever Beam with Piezoelectric Layer95108322710.47176/jcme.40.2.8561FAA. Panjebashi NaghshK. K. Esmaeili. TorkanpouriJournal Article20221231One of the new methods for powering low power electronic devices is the use of mechanical energies due to vibrations. In this method, the piezoelectric material is employed for converting the mechanical energy of vibration into the electrical energy. The advantage of this method is needlessness of using the battery charging system. In this paper, the functionally graded (FG) cantilever with the piezoelectric layer is considered as energy harvester system. The mathematical model of the system is constructed and the governing equation for electromechanical coupling is presented. Then the effects of the system parameters on the generated power is studied. Finally, by considering uncertainties in energy harvester parameters, the effect of uncertainties on the produced energy is investigated by Monte-Carlo simulation method for the first time. The results show that although the amount of generated power in the first natural frequency is higher than the other frequencies, but around the first natural frequency, the effect of uncertainties is increased and thus, the reliability of the energy harvester will be decreased.One of the new methods for powering low power electronic devices is the use of mechanical energies due to vibrations. In this method, the piezoelectric material is employed for converting the mechanical energy of vibration into the electrical energy. The advantage of this method is needlessness of using the battery charging system. In this paper, the functionally graded (FG) cantilever with the piezoelectric layer is considered as energy harvester system. The mathematical model of the system is constructed and the governing equation for electromechanical coupling is presented. Then the effects of the system parameters on the generated power is studied. Finally, by considering uncertainties in energy harvester parameters, the effect of uncertainties on the produced energy is investigated by Monte-Carlo simulation method for the first time. The results show that although the amount of generated power in the first natural frequency is higher than the other frequencies, but around the first natural frequency, the effect of uncertainties is increased and thus, the reliability of the energy harvester will be decreased.https://jcme.iut.ac.ir/article_3227_121dbbf57ed23baa63ed08d21647323b.pdfIsfahan University of TechnologyJournal of Computational Methods in Engineering2228769840220221231The Effect of Magnetic Field and Nanoparticle Shape on Heat Transfer in an Inclined Cavity with Uniform Heat Generation/AbsorptionThe Effect of Magnetic Field and Nanoparticle Shape on Heat Transfer in an Inclined Cavity with Uniform Heat Generation/Absorption109126322810.47176/jcme.40.2.8501FAM. NematiM. SefidM. S. Barghi JahromiR. JahangiriJournal Article20221231In the present work, the effect of magnetic field, changes in the angle of inclination of the cavity and the shape of nanoparticles on the flow field and heat transfer of water-alumina with uniform heat generation/absorption is investigated by Lattice Boltzmann method (LBM). The curved wall and the diagonal walls of the cavity are at a constant temperature of hot and cold, respectively. Nanoparticle volume fraction of 0, 0.02 and 0.04, Hartmann number of 0, 15, 30, 45 and 60, heat generation/absorption coefficient of -5, 0 and +5 and inclination angle of 45, 135 and 225 degrees are studied. The high accuracy of the results compared to previous studies confirmed the correctness of the code written in Fortran language. The results shows that in all cases, increasing the Hartmann number leads to a decrease in the maximum value of the streamlines and the average Nusselt number, with the lowest effect at 225 degrees. Also increasing the strength of the magnetic field leads to an average decrease of 28, 23 and 7% of the average Nusselt number for angles of 45, 135 and 225 degrees, respectively. Increasing the heat generation/absorption coefficient is a determining factor in the effectiveness of the magnetic field and adding nanoparticles, and increasing it reduces the amount of heat transfer. On average, heat generation reduces the average Nusselt number by 71, 98, and 145 percent for the angles of 45, 135, and 225 degrees, respectively. In general, the lowest value of the average Nusselt number is related to the angle of 225 degrees, but the effect of adding nanoparticles in increasing the average Nusselt number is the highest at this angle. Generally, an increase in the percentage of nanoparticles leads to an average increase of 12% in the average Nusselt number. The effect of nanoparticle shape is more apparent with increasing their volume fraction. The highest amount of heat transfer is related to the cylindrical nanoparticles, in which the average Nusselt number is on average about 6% higher than the spherical state.In the present work, the effect of magnetic field, changes in the angle of inclination of the cavity and the shape of nanoparticles on the flow field and heat transfer of water-alumina with uniform heat generation/absorption is investigated by Lattice Boltzmann method (LBM). The curved wall and the diagonal walls of the cavity are at a constant temperature of hot and cold, respectively. Nanoparticle volume fraction of 0, 0.02 and 0.04, Hartmann number of 0, 15, 30, 45 and 60, heat generation/absorption coefficient of -5, 0 and +5 and inclination angle of 45, 135 and 225 degrees are studied. The high accuracy of the results compared to previous studies confirmed the correctness of the code written in Fortran language. The results shows that in all cases, increasing the Hartmann number leads to a decrease in the maximum value of the streamlines and the average Nusselt number, with the lowest effect at 225 degrees. Also increasing the strength of the magnetic field leads to an average decrease of 28, 23 and 7% of the average Nusselt number for angles of 45, 135 and 225 degrees, respectively. Increasing the heat generation/absorption coefficient is a determining factor in the effectiveness of the magnetic field and adding nanoparticles, and increasing it reduces the amount of heat transfer. On average, heat generation reduces the average Nusselt number by 71, 98, and 145 percent for the angles of 45, 135, and 225 degrees, respectively. In general, the lowest value of the average Nusselt number is related to the angle of 225 degrees, but the effect of adding nanoparticles in increasing the average Nusselt number is the highest at this angle. Generally, an increase in the percentage of nanoparticles leads to an average increase of 12% in the average Nusselt number. The effect of nanoparticle shape is more apparent with increasing their volume fraction. The highest amount of heat transfer is related to the cylindrical nanoparticles, in which the average Nusselt number is on average about 6% higher than the spherical state.https://jcme.iut.ac.ir/article_3228_928759f4fad8ebc76e80a610f277322e.pdf